This invention relates to steam systems in which feed water is recirculated, as for turbine drive in a power plant or for marine propulsion, or in a generator of steam for industrial heating.
For economical operation of modern steam-generating systems, wherein condensate is the source of recycling feed water, it is important to remove contaminants, such as corrosion products and salts, and to improve feed water chemistry. A recognized technique has been to employ a demineralization filter which is operative upon the full flow of recirculating water. Such a filter and methods of its use are described in Levendusky U.S. Pat. No. 3,250,703. Filters of the character indicated are also known as condensate polishers; they rely on polishing resins (powdered ion-exchange resins) and often operate upon condensate available from the hot well of the condenser, at about 110.degree. F. After demineralization, the water is suitably preheated and pumped for recycled entry into the steam generator. In a typical modern power plant, the preheating is to about 450.degree. F. and the flow rate is in the order of 12,000 gallons per minute. The polishing resins are expensive and, by their temperature-sensitive nature, limit the location at which they may be used in the total system.